Abstract: An oxygen concentration detecting device comprises a solid electrolyte body, inner and outer electrodes formed on the opposite sides of the solid electrolyte body, and a protective layer formed on the outer electrode and comprised of coarse particles and fine particles mutually bonded through an inorganic binder while substantially keeping the original forms of the both types of particles. A ratio of an average particle size, RB, of the coarse particles to an average particle size, RA, of the fine particles of 30:1 or above, and a content, WA, of the fine particles in the protective layer based on the total content, W, of the content, WA, of the fine particles and the content, WB, of the coarse particles on the weight basis is in the range of 15 to 80 %. A method for fabricating the detecting device having such a protective layer as set out above is also described.

Abstract: An oxygen concentration detector includes a one-end closed cylindrical oxygen sensing element having an inside electrode, outside electrode provided on the inner side and outer side respectively, an electrode protecting layer made up of ceramics porous member provided further outside the outside electrode, and a trap layer 1 of ceramics porous member having a surface roughness of 20 to 100 .mu.m measured according to a 10 point mean roughness measurement and provided outside the electrode protecting layer is employed. By dipping the to-be-detected gas side surface of an oxygen sensing element into a slurry with coarse heat-resisting metal oxide particles, 2 to 50 .mu.m in average grain size, dispersed, depositing the slurry on the surface of a protective layer of an oxygen sensor element, thereafter drying and baking the deposit, a porous poisonous substance trap layer, 10 to 500 .mu.m thick, is formed.

Abstract: A ceramic heater which can be produced easily, induces no increase of production cost and can restrict the resistance change of a heating body due to migration. According to the present invention, a gap is formed between a ceramic sintered body and a heating body. Thus, migration in which cations are seized within the gap is caused so as to impede the cations from entering into the heating body. This makes it difficult for the cations to migrate and the volume in which the heating body is expanded is secured by the gap 13.

Abstract: An oxygen concentration detector provides high durability by increasing the thermal stability of coating layers applied to an electrode face thereof. A catalyst layer is formed on an outer surface of an electrode at the analysis gas side of a partition wall made of an ion oxygen conductive ceramic for generating electromotive force according to the difference between the concentration of oxygen in the analysis gas and the concentration of oxygen in the reference gas. The catalyst layer is composed of heat resistant ceramic particles and a particulate metallic catalyst made of platinum, rhodium or the like, supported by the surface of the heat resistant ceramic particles. The catalyst layer is formed so that the catalyst is supported by the heat resistant support particles. The support particles are heat treated to grow to a particle size so that particle growth can be restrained when the support particles are exposed to the exhaust gas from an internal combustion engine.